1. Technical Field
The present invention relates to analytical strips and more particularly, to an analytical strip for biochemical and immunological assays.
2. Description of Related Art
Analytical strips are conventionally used in biochemical tests and immunological tests. A typical analytical strip has a substrate or a base formed with sunken channels or micro-channels and processed with hydrophobic and hydrophilic surface treatment. Since the channels are bordered by non-absorbent material, and fluid samples to be tested are usually viscous compositions containing, for example, protein or carbohydrate, a fluid sample flowing in the channels tends to adhere to surfaces of the channels and cannot be fully reacted. Consequently, the fluid sample is wasted, if not leading to errors of test results.
In addition, the conventional analytical strips are provided with micro-channels to facilitate fluid delivery, in which the micro-channels cause a capillary action that draws a fluid sample through the channels to a reaction/detection region. Alternatively, a fluid sample may be introduced into the channels with a driving force provided by, for example, a pressurizing means or a vacuum- or negative pressure-generating means, thereby propelling the fluid sample through the channels. Another approach to promoting fluid delivery is to provide the channels with one or more micro-actuators or micro-valves through which a fluid sample will pass successively before arriving at a reaction/detecting region. However, in any of the aforesaid approaches, air bubbles of various sizes tend to be generated in, or entrained into, fluid samples to be tested after the samples are introduced into the channels. These bubbles, when causing channel blockage, may result in test errors or even test failure. Moreover, installation of the micro-actuators or micro-valves will add to the overall difficulty of design and the cost of analytical strips.
Besides, during manufacture of the conventional analytical strips, the channels or microfluidic-channels are usually formed on the substrates by micro-injection forming or imprinting, using expensive die making process such as micro-machining or LIGA (abbreviation of “Lithographie GalVanoformung Abformung”, or “Lithography Electroforming Micro Molding” in English) which, coupled with early wear and tear of molds, increases the total cost incurred in making analytical strips.
Hence, the residual of the fluid sample in the channel renders testing inconvenient and time-consuming. In addition, the manufacturing cost of traditional analytical strip is usually considerable.